1. Technical Field
One or more embodiments of the present invention relate to an electroforming method for molding metal products.
2. Background Art
As a method of manufacturing a fine metal product that is difficult to produce with machining, electroforming technology (electroforming) has been known. This is a thick electroplating process of thickly plating a metal on a mold and removing the thick-plated film (the metal-formed product) from the mold, thereby forming a metal product. In general, electroplating with a thickness exceeding 20 μm is called electroforming.
For example, in a method disclosed in Patent Document 1, the surface of a metal-made mold is coated with a photoresist, and is then patterned to form a resist film with an opening of a desired pattern, and then a metal is electrodeposited inside the opening of the resist film, that is, on a part of the surface of the mold not coated with the resist film to form a metal layer (a thick-plated film). Then, the metal layer is removed from the mold, thereby obtaining a fine metal-formed product of a desired shape.
However, in the process of electrodepositing a metal on the surface of the mold, part of an electric current interrupted by the resist film flows into an electrodeposited part near the resist film to partially increase the amount of electrodeposition, resulting in a trouble of unevenness of the thickness of the metal layer. In particular, the metal layer bulges at its edge portion of a surface of the metal layer (a surface opposite to the surface electrodeposited on the mold) in contact with the resist film, thereby causing the thickness of the metal layer to partially increase.
For this reason, in the method disclosed in Patent Document 1, the metal layer is formed so as to be slightly thicker than the resist film, and the surface of the metal layer is then polished to be smoothed, thereby making the thickness of the metal layer uniform.
As described above, in conventional electroforming, the surface of the metal layer (a surface opposite to a surface electrodeposited on a mold) cannot be controlled, which considerably restricts the moldable shape of a metal-formed product. Also, in order to put the shape of the metal-formed product properly, polishing or the like has to be performed after forming, which decreases efficiency of manufacture and increases cost of manufacture.
Patent Document
Patent Document 1: Japanese Unexamined Patent Application Publication No. 8-225983 (paragraph 0002, FIG. 7)